Method for drying materials



Aug- 28,,1945- J. E. STEINER 2,383,694.

, METHOD FOR DRYING MATERIAL Filed Sept. 15, 1942 2 Sheets-Sheet 1 I5 I21 4 CHARGE 7 DISCHARGE 5 i 5 J a t i a J h @QQQGQ A Jo/m E. Sfe/nerINVENIOR.

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ATTORNEY Auig- 1945- J. E. STEINER 2,383,694

METHOD FOR DRYING MATERIAL Filed'Sept. 15, 1942 2 Sheets-"Sheet 2 8INVENTOR.

' BY W h-QXM ATTORNEY Patented Aug. 28, 1945 2,383,694 METHOD FDR. name.MATERIALS John E. Steiner, Cambridge, Minn, assignor to Hercules PowderCompany, Wilmington, Del., a corporation of Delaware ApplicationSeptember 15, 1942, Serial No. 458,416

3 Claims. (01. 18-48) This invention relates to a method for dryingmaterials of various kinds and, more particularly, to a method fordrying materials of the wet-solids type, such as, curd in themanufacture of casein.

Wet-solids, as they usually come to a drying machine, are in extremelypoor form for either eflicient or uniform drying. The most common formsare lumpy masses, large slabs of filter cake, or broken filter cake withparticles of widely varying sizes. In any of these forms there is verylittle surface area exposed in proportion to the total mass of material.As a result, drying is a slow process because evaporation of moisturefrom the material can take place only at the exposed surface. Thevariation in the sizes of the units or pieces of material results in alack of uniformity in drying. Where this variation in size is great, thedrying problem is complex, and the time of drying cycle is increased inorder to sumciently dry the largest of the various units.

Furthermore, in the drying of material wherein tralized. These packedareas under the same pressure of drying medium as the unpacked areas,ofier considerably more resistance to the passage of the drying mediumtherethrough. As a result, holes are blownthrough the areas of leastresistance and the drying medium passes therethrough without eflectivelycontacting the other areas. This, of course, causes uneven drying andwet spots in the layer of treated material.

An object of this invention is the provision of a method for conveyingmaterial in layer form of predetermined thickness through a dryingchamber without substantially disturbing the thickness of the layer andwith scoring of the layer to insure the uniform passage of drying mediumtherethrough.

Another object of this invention is the provision of a method forconveying material in layer form through a portion of a drying char andthen reducing the layer of material into individual units of apredetermined size and conveying said individual units through a remaiportion of the drying chamber.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claims.

Generally described, the present invention provides a method ofcontinuously drying wet-solids material which comprises distributing thematerial in a layer of uniform depth and scoring the distributedmaterial to permit a dryingmedium to be freely circulated therethrough.

A preferred embodiment of the invention has been chosen forpurposes ofillustration and description and is shown in the accompanying drawingsforming a part of the specification wherein reference symbols refer tolike parts wherever they occur.

. Figure 1 is a diagrammatical vertical sectional view taken lengthwiseof the run of the conveyor, of one form of apparatus for the embodimentof the invention. Figure 2 is an enlargedsectional view taken along thesection 2-2 of Figure 1; Figure 3 is a front elevational view of a combfor channeling material, with the material and the conveying belt shownin section; Figure 4 is a sectional View taken along the section M ofFigure 3; Figure 5 is a front'elevational view of two reciprocatingcombs for uniformly channeling material, with the comb-supportingmembers, the material, and the conveying belt shown in section; Figure 6is a fragmentary plan view of Figure 5; Figure 7 is a sectional view enalong the section l-l of Figure 5; Figure 8 is a fragmentary plan viewof finger-like members for engaging partially dried layer material andreducing it to individual units; and Figure 9 is a v sectional viewtaken along i i-t of Figure 8.

In Figure 1, Figure 2, Figure 3, and Figure d a drier l of conventionaldesign has an endless conveyor belt t'of open mesh top extendingtherethrough. The conveyor belt 3 is preferably of the sectional typewith continuous side guards and with sections oi the mesh fastened toand carried by roller chains at the sides. This type conveyor permitsbut very little sag in the individual sections of the conveyor belt. Amaterial 5 to be dried is charged in a layer of uniform depth, bysuitable means (not shown), upon the conveyor belt 8. This material isprogressed by the conveyor belt and encounters a comb "5 provided with aplurality of teeth t. The comb l is rigidly amxed to the bench la of thedrier l or other suitable supporting means so that the lower extremityof the teeth 9 barely clear the top surface of the t combs 55 andthrough the layer of material, without creating any "blows." This sameair then goes backto the fans and the cycle of recirculation iscontinuously repeated, as represented by the arrows l5, during-thepassage of the material 5 through the drying chamber I3.

From the drying chamber 13, the material 5 passes into drying chamber 2!which has motordriven fans and steam heaters i'I disposed below andabove, respectively, of the conveyor belt 3. Circulation is similar tothat discussed above for chamber It, with the exception that thedirection of flow of the air is opposite, as represented by the arrows23. By the time the mate rial 5 enters the chamber 2|, it is partiallydried and becomes somewhat brittle and as the material continues to passthrough chamber 2 I, the material encounters a plurality of finger-likemembers 25 (see Figures 1, 8, and 9). These members are supported byrods 21 which in turn are rigidly secured to the sides of the drier lb,or other suitable means. The members 25 are inclined, having their lowerextremities in proximity to the top of the conveyor .belt 3, so that thepartially dried material 5, upon encountering the members 25, ridesthereupon, causing the material 5 to be broken into units ofsubstantially uniform size (see Figure 9). The material 5 is thereaftertreated in the form of individual units in the remaining portion of thedrying chamber 2| from which it is discharged in the conventionalmanner.

Referring now more specifically to Figures 5, 6, and 7, anotherembodiment of'the invention is presented for positively reducing amaterial to be dried into individual units of uniform size. A comb50 anda comb 52 are slidably aflixed to the bench la of the drier l or othersuitable means. These combs 5D and 52 have a plurality of teeth 54 and56, respectively, the lower extremity of which barely clears the topsurface of.the.conveyor belt 3. The combs should be preferably in spacedrelationship, as shown, because if the teeth of the comb or combs aretoo closely spaced a piling up of material will result, therebydestroying uniformity. The slidably affixed combs 50 and 52 are actuatedwith a reciprocative movement by earns 58 and 50, and cams 52 and 54,respectively. The earns 58 and 52 are rigidly secured to a drive shaft56 and the cams and 54 are rigidly secured to a drive shaft 58. Thesedrive shafts may be driven from a separate source of power or may \bedriven in association with the driving mechanism for actuating the cveyor belt 3. The reciprocative movement of 52 may also be accomplishedby providing protrusions on the apron of the conveyor belt 3. Thespecific means for reciprocating the combs does not constitute a part ofthis invention, as such expedients are obvious to those skilled in theart, however, the particular arrangement of the combs to. achieve auniform scoring or channeling of the material to be dried doesconstitute a part of this invention. In this respect, the teeth 550icomb 52 channel the material 5 as it advances, as represented by thearrow 15. The teeth 54 of the comb 55, being spaced equidistant andintermediate of the teeth 55, channel the material 5 as it advances, asrep- 2,sea,ec4 I resented by the arrow 12. This combination, inassociation with the cams 55, 50, 52, and M in synchronous associationwith the rate of travel developing 'tially throughout of the conveyorbelt 3, gives a square-like configuration of channeling (see Figure 6).It is evident that other uniform configurations in the material may beemployed, such asan intersecting wave-like configuration depending uponthe particular cut of the cams and/or the cyclic method of rotating saidcams, but the square-like configuration is preferable from a standpointof uniformity of moisture travel to the exposed surface whereevaporation takes place and a standpoint of ease of breaking the layerof material into individual units. The material 5 having a uniformconfiguration of scoring or channeling is reduced to individual units inthe same manner as set forth above in the description of the preferredembodiment.

For the drying of some materials, it is unnec- I essary to reduce thematerial to individual units to accomplish effective drying, as thescoring of the material alone will suflice. For example, in the dryingof curd for the manufacture of casein a uniform layer of rennet caseinwas placed upon the conveyor belt 3. The comb 1 had its teeth 9 spacedat one and one-half inch intervals. The curd was progressed through thedrier and was scored with longitudinal channels which were foundsuiiicient to prevent the layer of curd from blows which had occurredwhen the curd was unscored. For the drying of acid casein it was foundpreferable to have the teeth 9 spaced at three-fourth inch intervals. Inboth cases the casein was effectively dried with a high degree ofuniformity.

Generally, however, materials of many kinds, such as sulphur sludge,phosphate fertilizer, calcium carbonate, magnesium carbonate, and limeputty, are more efliciently dried by scoring the material and reducingthe scored material to individual units for complete drying.

The advantages of the present invention reside in the speed of drying,the uniformity of drying, and the drying of the material in shapes ofuniform size, whereby all the shapes are dried perfectly alike.

What I claim and desire to protect by Letters Patent is:

1. A method of continuously drying wet-solids material of a semiplasticnature which is sumciently stiff to retain channels after they have beenformed in said material which comprises distributing the material in a,layer of uniform depth; scoring the distributed material substanitsdepth to form channels therein, and subjecting the scored material to adrying medium under sufiicient pressure to cause passage of said dryingmedium through the bottom wall of each of said channels.

2. A method of continuously drying wet-solids material of a semiplasticnature which is sufficientlystiff to retain channels after they havebeen formed in said material which comprises distributing the materialin a layer of uniform depth, scoring the distributed materialsubstantially throughout its depth to form channels therein, subjectingthe scored material to a drying medium under suflicient pressure tocause passage of tom wall of each of said channels to partially dry thescored material, breaking the partially dried scored material intoindividual units, and subjecting the individual units to the dryingmedium to complete drying.

said drying medium through the boting the scored material to a dryingmedium under sufllcient pressure to cause passage of said drying mediumthrough the bottom wall of each oi said channels to partially dry thescored material, breaking the partially dried scored material intoindividual units of uniform configuration along said channels, andsubjecting the individual units to the drying medium to complete drying.

JOHN E. STEINER.

